1. Field of the Invention
The invention relates to an electric switch wherein a housing contains an insulating screen which is inserted at high speed between the two contacts to de-stabilize the arc that strikes when the contacts part by shearing the arc against a neighbouring insulating wall.
Switches of this type, which result in extremely fast current breaking, can be used to advantage either in apparatus or combinations of apparatus designed specifically to protect lines against short-circuit currents, or else in breaking devices designed to open on high steady-state currents.
2. Description of the Prior Art
Screened switches such as those described above are already known, wherein the screen is propelled either by electro-magnetic devices assembled in series, or by elastic means.
In any case, it is not easy to establish a synchronism and/or relation between the screen motion speed and the increase rate or level of the current to be opened; the purpose of the invention is therefore to provide suitable means so that a screened switch is able to open current in such a way that breaking speed increases as current increases, and to take advantage of the energy of the arc that strikes when the contacts part.